Let’s reword the question to make it simpler to understand:
Keeley pays $3.20 per shirt + 5% for shipping.
She sells them at the carnival for 150% the price she paid.
First of all we should work out how much the 5% shipping cost Keeley.
If the shirts are $3.20 that means 10% is $0.32, to get 5% we divide that by 2. This means 5% is $0.16, therefore shipping is $0.16.
The total price Keeley pays per shirt is $3.20 + $0.16 = $3.36.
Now let’s find out 10% of $3.36, which is $0.336, then multiply that by 15 to get 150%:
5.04
Therefore Keeley sells each shirt for $5.04